Adhesive connection between an adhesion surface of a body and a corresponding adhesion surface on the outside of a machine housing

ABSTRACT

A body to be bonded to a machine housing. The body may include a substantially flat adhesion surface provided with an undercut portion. The undercut portion may form a disc-like shoulder and an acute, wedge-shaped edge with the periphery of the adhesion surface, wherein the wedge-shaped edge is oriented to face away from the adhesion surface and to oppose the shoulder. The machine housing may further be provided with grooves adapted to improve the strength of a bond between an adhesive material and the adhesion surface.

DESCRIPTION OF THE INVENTION BACKGROUND

[0001] The invention relates to a metallic body to be bonded to theoutside of a housing, i.e. shell or encasing, especially a vibratingmachine. In addition, the invention especially relates to the housing ofa sensor intended for transforming a physical quantity, in particularvibration, into a corresponding electrical signal, or relates to anadaptor for attaching such a sensor to the housing of a machine, thebody exhibiting a substantially flat adhesion surface, and the inventionrelates to an adhesive connection between the adhesive surface of such abody and a corresponding opposite adhesive surface situated on theoutside of a machine housing.

[0002] Sensors for transforming a physical quantity into a correspondingelectrical signal, for example, acceleration sensors for transformingsignals of vibration into a corresponding electrical signal, frequentlyhave to be fastened to the housing of a machine in a durable andreliable manner, as well as in a suitable manner that allows anundistorted and essentially undamped transmission of the physicalquantity to be transformed. This should be done either by direct actionor, in the case the sensor is intended for easy dismounting, by means ofan adaptor which has to be fastened to the housing of a machine in acorresponding manner.

[0003] A known method of attaching will provide a sensor or adaptor tobe screwed onto the housing of a machine, such housing being providedwith a threaded hole of comparatively extensive diameter, and a solidthreaded stub that extends from the housing of the sensor or of anadaptor, will be screed into said threaded hole. This known method offastening requires considerable amounts of work and is timeconsuming,especially in the case the threaded hole will have to be provided to themachine after the machine has been placed to its intended workingposition, which is the most frequent case.

[0004] In addition, the aforementioned known method of attaching asensor or and adaptor to a housing of a machine will not be applicablein case the housing must not be drilled into.

[0005] In order to avoid the aforementioned difficulties it has beensuggested already, to bond the sensor or the adaptor to the housing of amachine by gluing.

[0006] Especially with vibrating machinery the problem had not yet beensolved, to attain an adhesive connection between a sensor or an adaptorand the housing of a machine which will be long-lasting and which willhave strength of such quality to assure a reliable bonding.

[0007] The underlying problem, and therefore an object of the invention,is to design both the body to be bonded and the adhesive connection insuch manner, that a permanent attachment of the sensor will be effectedsolely by gluing, i.e. without the necessity of drilling a screw hole(tap hole) of large dimension into the housing of a machine.

SUMMARY OF THE INVENTION

[0008] The aforementioned problem will be solved for one part byproviding a design of the metallic body to be bonded in accordance withclaim 1 and for another part by the specific creation or design of theadhesive connection between such body and the housing of a machine inaccordance with claim 9.

[0009] The characteristics of claim 1 will assure, that an adhesive (orglue) which is supplied in a sufficient amount between metallic body andthe housing of a machine will not only be distributed reliably about theadhesion surface while the metallic body and the housing of the machinewill be made to rotatably approach each other. Moreover, the adhesivewill also be drawn into the region of an undercut direct adjacent to theadhesion surface, in a claw-giving fashion, onto the dorsal (back) sideof the wedge shaped form (of the undercut). This will produce anespecially strong connection between a housing of a machine and themetallic body once the adhesive has cured. A prerequisite for this kindof connection is, that the amount of adhesive that is supplied to a bodydesigned according to claim 1 and a housing of a machine, will be morethan an amount that would be sufficient only to cover the adhesionsurfaces. Also, the metallic body will have to approach the housing of amachine in a rotating way about an axis of rotation that isperpendicular to the adhesion surface, preferably about ca. the centrallongitudinal axis of the metallic body.

[0010] The invention may not only be used with advantage when bondingsensors or adaptors for sensors to a housing of a machine, but also isof advantage for attachment of any metallic body to machines by bondingor gluing, in particular for attaching to those machines that mayvibrate and which require a permanent connection of high strength ofstability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Subsequently, the invention will be explained in more detail,referring to the drawing of a preferred embodiment.

[0012] In the accompanying drawing, it is shown by

[0013]FIG. 1: a side view, partly as a longitudinal section, of ametallic body relating to the form of a sensor or an adaptor for asensor, the body being attached to the housing of a machine

[0014]FIG. 2: a cross section along cutting line II-II of FIG. 1 throughthe adhesive connection between the metallic body and the housing of amachine

[0015]FIG. 3: a plan view of the adhesion surface on the housing of amachine, intended for bonding the metallic body onto it, and

[0016]FIG. 4: a cross section (to enlarged scale) of a thread groovingstud that is additionally provided for an adhesive connection accordingto FIG. 1.

[0017] In FIG. 1 a metallic body 1 is shown from a side view, beingadhesively bonded to a housing 2 of a machine. The housing 2 of amachine is shown in longitudinal section along a sectional plane whichincludes a centerline 3, which centerline defines a rotational symmetryof body 1. Also, adhesive 5 is shown in a cutaway view along saidsectional plane.

[0018] In the drawing if FIG. 1 only a part of the housing 2 of amachine is shown, being of proximity to body 1. The machine mayconstitute for example a motor, or a generator, or the like, thevibrations of such machine being measured e.g. in order to monitor thewear of a rolling-bearing provided for its rotor. For this purpose, anacceleration sensor is set onto (lit: in) and contacting the metallicbody 1, or else, body 1 constitute an adapter for receiving a separatesensor intended for acceleration measurements, such that the sensor maybe fastened to the adaptor, but allowing for easy disengagement of same.

[0019] Metallic body 1, on its face side that is oriented towards thehousing 2 of a machine, exhibits a disk-like shoulder 4, body andshoulder being unitary and made from the same piece of material. Also,the face area of body 1 oriented towards the housing 2 of a machine isconstituting an adhesion surface 4 a for adhesively bonding body 1 to anopposite adhesive surface 2 a of a housing 2 of a machine.

[0020] The disk-like shoulder 4 is formed in such way, that the adhesionsurface 4 a is adjoined or supplemented, towards the central volume ofbody 1, by an undercut 4 b which forms an acute, wedge-shaped edge withthe periphery of the adhesion surface 4 a. Thus, the mentioned shoulderwill be formed like a truncated cone turned upside down. Using a designof this kind will effect a sufficient amount of adhesive 5 that isapplied to adhesive surface 2 a and which amount is greater compared toan amount required for only covering adhesion surfaces 2 a and 4 a, tobe drawn into the undercut 4 b in a reliable manner. After curing, theadhesive will set behind the undercut in a claw-like fashion around theperiphery of the disk-like shoulder 4. By this an especial strong andvibration-resistant permanent connection between metallic body 1 andhousing 2 of a machine will be obtained, as soon as the adhesive hashardened.

[0021] In order to even improve the bonding strength of adhesive 5against adhesion surface 4 a of body 1, this surface will be pre-formedwith multiple grooves 6, as shown in FIG. 2, and the single grooves 6 ahaving an arc-like curvature, e.g. the demonstrated embodiment showsarcs of circles that intersect each other.

[0022] In order to improve the bonding strength of the adhesive 5against an opposite adhesion surface 2 a of the housing of a machine,this surface is also provided with a set of multiple grooves 7, thesingle grooves 7 a of which intersect according to a pattern of checkers(karoartig). The embodiment, presented as an example, shows thesegrooves to be straight. However, they may exhibit an arc-like curvaturecomparable to grooves 6 a of adhesion surface 4 a.

[0023] It is preferred, to have opposite adhesive surface 2 a of housing2 of a machine, as well as adhesive surface 4 a of body 1, ofessentially flat shape.

[0024] Usually, it will take some time before the adhesive has hardened,which has been applied to adhesion surfaces 2 a and 4 a and whichadhesive, after said adhesion surfaces have been placed closely to eachother, has progressed into undercut 4 b. Therefore, it is advised tostabilize the position of body 1 relative to housing 2 by additionalmeans. For this purpose, it is intended to utilize a stud 8 which isprovided with a thread for cutting or generating threadlike grooves, thecross section of said stud being of polygon shape (cf. FIG. 4). Stud 8may be screwed into a central bore-hole within adhesion surface 4 a oralso into a central bore-hole of adhesion surface 2 a of a housing 2 ofa machine, with the thread of the stud being worked into the walls ofsaid bore-holes, and the bore-holes being oriented perpendicular to thementioned adhesion surfaces.

[0025] The primary function of this thread grooving stud 8 is notintended to fasten body 1 onto a housing 2 of a machine, but rather tosecure body 1 to its predefined final position, whilst the adhesive hasnot hardened. Of course, this stud will improve the strength of theconnection to a certain degree once the adhesive has hardened, however,the adhesive connection is of such design, that it will exhibitsufficient permanent strength of the bonding after the adhesive hashardened, even without this thread-grooving stud 8.

[0026]FIGS. 2 and 3 do not show the thread-grooving stud 8. In case itis allowed to drill into the housing 2 of a machine so as to furnish acorresponding borehole 2 b, this stud will be screwed into bore-hole 4 cof body 1 as well as into borehole 2 b of housing 2. However, anintended adhesive connection from body 1 to housing 2 of a machine maybe rendered as well, in case it is not allowed to make a bore-hole 2 binto a corresponding housing 2 of a machine.

[0027] According to the invention, it is preferred to use a metal basedglue 5 consisting of a plastic base-material and a metallic filler (e.g.so called plastic-steel). This not only will yield the intendedmechanical connection of very high strength between body 1 and thehousing 2 of a machine, but also will produce a most possible undampedand undistorted transfer of a physical quantity to be studied, which isvibration in the embodiment discussed as a preferred example, indirection towards the sensor. The reason for this is, that an adhesiveof this type has also very good properties regarding that aspect,because of its incorporated metal filler.

What is claimed is:
 1. A metallic body (1), to be bonded to the outsideof a housing (2) of a machine, especially a vibrating machine, inparticular the metallic body (1) constituting a housing or shell of asensor, which sensor is capable of converting a physical quantity, inparticular a physical quantity related to one or more aspects ofmechanical vibration, into a corresponding electrical signal, or themetallic body (1) in particular constituting an adaptor for attachingsaid sensor to the housing of a machine, the body (1) exhibiting asubstantially flat adhesion surface (4 a), characterized in that, thatthe adhesion surface (4 a) is adjoined or supplemented, towards acentral volume part of the body, by an undercut (4 b) which forms anacute, wedge-shaped edge with the periphery of the adhesion surface (4a).